Plate clamp for printing cylinders



c. s. CRAFTS 2,356,305

PLATE CLAMP FOR PRINTING CYLINDERS Filed April 25, 1942 2 Sheets-Sheet 1 Aug 22, 1944.

c. s. CRAFTS I PLATE CLAMP FOR PRINTING .CYLINDERS 2 Sheets-Sheet 2 Filed April 25, 1942 Patented Aug. 22, 1944 UNITED STATES PATENT OFFICE PLATE CLAMP FOR PRINTING CYLINDERS Application April 25, 1942, Serial No. 440,457

6 Claims. (01. 101-378) The present invention relates to a novel and improved stereotype plate cylinder particularly adapted for operation at extremely high speeds.

Objects and advantages of the invention will be set forth in part hereinafter and in part will be obvious herefrom, or may be learned by practice with the invention, the same being realized and attained by means of the instrumentalities and combinations pointed out in the appended claims.

The invention consists in the novel parts, constructions, arrangements, combinations and improvements herein shown and described.

The accompanying drawings, referred to here,- in and constituting a part hereof, illustrate one embodiment of the invention, and together with .the description, serve to explain the principles of the invention.

Of the drawings:

Figure 1 is a fragmentary top plan view of a typical and illustrative embodiment of the present invention;

Figure 2 is a detailed section taken on the line 22 of Figure 1;

Figure 3 is an exploded perspective view of a center clamp in accordance with the present invention;

Figure 4 is a fragmentary longitudinal view of one of the plate clamps shown in Figure 1 with two plates held in clamped position;

Figure 5 is a similar view showing the clamps unlocked to allow removal of the plates from the cylinder;

Figure 6 is a similar view showing a single plate held in clamped position; and

Figure '7 is a detailed view showing a member preventing turning of the screw rod and used in the present embodiment.

The present invention has for its object the provision of a novel and improved high speed printing cylinder to receive semi-cylindrical stereotype printing plates such as are used for the printing of newspapers. A further object is the provision of a cylinder having plate clamps which securely lock the plates to the cylinder without subjecting the plates to unduestrain such as might damage or break the plates during operation at extremely high speeds over a relatively long period of time. The invention also provides a plate cylinder having clamps which will securely clamp the end of a printing plate even when its end is not accurately circumferential or is warped or bent. Still another object is the provision'of a plate clamp'which grips the end of the parti-cylindrical plate' withresilient pressure so that it is securely held even if the end of the plate is slightly irregular.

It has been customary to provide rotary printing cylinders such as are used on high speed newspaper presses with a center ring on each side of which are positioned two sets of axially spaced plates, which are held tothe cylinder by engagement of their ends with the center ring, a set of intermediate clamps and a set of outer plate clamps. However, the usual construction of such clamps is such as toexert undue strain on certain portions of the plate ends, when the semi-cylindrical plates are warped or not cut off on a straight line, so as to leave a large space along the curved edge of the plate not securely clamped, thereby increasing the tendency of the plate to work loose or break, so as to cause damage to the machinery.

In accordance with the present invention, the intermediate clamps between the adjacent edges of the inner and outer plates at each side of the central ring are resiliently urged towards their cooperating plate ends and the outer plate clamps are also resiliently urged towards the center ring and the outer edge of the outer plate, thereby insuring constant, uniform engagement with the plate ends, avoiding excessive pressure at any point along the plate ends, and generallyincreasing the security withwhich the plates are held to the cylinder while minimizing the possibility of plate breakage even at extremely high speeds and during long runs.

It will be understood that the foregoing general description and the following detailed deprinting cylinder I0 to receive semi-cylindrical stereotype printing plates of conventional form.

The cylinder, as is usual, may receive and hold four plates lengthwise and two around, making a total of eight plates, each plate corresponding to one newspaper or two tabloid pages. The central plates are designated as l2 and the outer plates are designated l4, one only of each being shown, as the other end of the cylinder may conveniently be a duplicate of that shown.

At the center of the cylinder l0 and extending circumferentially thereof is a conventional center ring I6 which is undercut to receive and overlie and thereby clamp the inner arcuate beveled edge 18 of' thein-ner plate I2.

, Extending axially of the cylinder surfac'e'area being enlarged to give adequate clearance with respect to the plate clamp which is to slide in H the slot.

At the end of the cylinder is provided meansfor moving the plate clamps to and from plate clamping position to release or secure the printing plates and these means comprise a common end plate or look plate 28 provided with means (not shown) for moving the plate towards and,

from the cylinder and may be generall similar to that shown in the patent to Evensen and Hermanson 1,658,035. Within each of'the slots 2|] is provided an internally and externally threaded screw rod 3|! having an adjustable extension 36, the outer end of which rod 30 projects through a suitable aperture in the plate 28 and is headed to facilitate turning. A collar 32 is provided on the rod 30 and between the collar 32 and plate 28, a heavy compression spring 33 is maintained under compression to be further compressed when the plate 28 is moved towards the end of cylinder l0.

Near the outer end of each rod 36 is provided a plate clamp 55 threaded to fit the external threads of the rod and having an undercut jaw 38 to engage the outer beveled edge of the outer plate l4, the clamp 55 being generally the same in cross-section as the slot so that it is easily slidable therein and yet is held against substantial radial movement with respect to the cylinder. The position of the clamp 55 may be varied by the threaded rod 3|] to accommodate plates of diiferent widths, and the inner threads of rod 30 are preferably of the same hand and of one-half the pitch of the outer threads so that the rod 46 is moved inwardly of the cylinder at one-half the speed of the inward movementof clamp 55 as rod 30 is turned, thereby simultaneously varying the position of the intermediate clamps 40, 4| and the outer clamp 55 to accommodate varying widths of plates.

The plate clamps which are between the adjacent edges of the plates l2 and I4' comprise the members 40, 4| arranged in working pairs and having oppositely facing undercut jaws 42, 43 extending beyond the cylindersurface and each adapted to engage a beveled edge-of a plate, Members 46 and 4| are formed with oppositely extending recesses 44 and are apertured to receive rod 46 around which is coiled a strong compression spring 41 which is received within recesses 44 said spring being of less strength than spring 33 but of 'su'fficient strength to normally exert plate holding pressure on the plate through the jaws 42, 43.

The members 40 and 4| are provided with apertures, alined axially of the cylinder, and through which passes the rod 46, whereby said members are slidably mounted on the rod. At its inner end, rod 46 is provided with a stop nut 45 for limiting the movement of member 4| away from member 4!] and by which the members 40'and 4| mat be drawn along the slot towards an end edges of the of the cylinder, while at its other end, rod 46 is provided with a threaded portion 49 to bereceived in the threaded interior of the rod 30, thereby permitting the rod 46 to project more or less from the rod 36. Intermediate the ends of rod 46 is a plate 5|, held by nuts 52 and 53 which holds the rod 46 against turning as rod 36 is turned. Nut 53 forms a stop which limits the movement of member 46 away from member 4| and provides a means whereby member 40 may be shifted inwardly on rod 46 to move member 4| to the clamping position shown in Fig. 6 so that an inner plate l2 may be clamped in working position in the absence of an outer plate M at the same side of the cylinder.

. Filler blocks are provided in the grooves 20 to providea cylindrical surface flush with the cylinder andmay comprise the fixed block 60, and

hollow blocks 6|, 62, 63 and 64 which may be free to slide in the grooves between the plate 5| and the clamp 55, as well as a hollow block 66 to telescope with the inner end of the rod 46.

'Whil-e clips '46, 4| and 55 may be of various forms, they are preferably of uniform cross section and have parallel faces H), H which fit closely with the upper and lower parallel surfaces of the groove 20 in which they slide, and are also formed with parallel surfaces 13 to prevent side play, by close fit with the almost radial but parallel sides of the narrow portion of the groove. Clearance is allowed on the bevel faces of the clamp to clear the edges 2| of the groove, and the bottom sides of the clamps are likewise clear of the wide sides of the groove, as is the arcuate portion of the'clamp clear of the surfaceof the cylinder.

In the operation of the illustrative embodiment:

As shown in Figure 5 the plate 28 is withdrawn from the cylinder end thereby relieving a portion of the pressure on the several springs 33 and pulling rods 30 and 46 to the left, at the same time separating clamps 4| from center ring l6 and allowing springs 41 to space clamps 40 and 4|. The inner plate I2 is then slid into place as shown, and as outer clamps 55 are likewise moved to the left by release of the plate 28, printin'g plate l4 may be placed on the'cylinder. The

end plate 28 is then moved towards the cylinder end, to force rods 30 and 46 inwardly of the cylinder by further compression of the compressed springs 33, thereby moving clamps 55 into engagement with the outer beveled edge of plate tacting at the location where, since the outer edge of the plate I2 and the inner edge of plate M are not truly paralleLcompensation is necessary because the space between these plates is a minimum, all other sets of these clips remaining slightly spaced apart'by the action of the springs 41, this relationshipybeing illustrated in 'Figure 1'. Further inward movement of the plate ,28 to the locked position causes it to separate from nuts 6! on the outer end of rod 36, thus further compressing springs 33 and transferring their full spring load onto plate |4 aridthrough springs 41 and clamps 40, 4|, s'liding'on'rods 46,

onto plate l2, thus causing plate l2 to be resiliently but firmly held by ring I6 and clamps 40 under the compression of springs 41 while the outer plate I4 is held by clamps 4B and 55 under the compression of springs 41 and 33, respectively, as shown in Figure 4.

Different widths of plates may be accommodated by turning each rod 30 thereby causing the corresponding clamp 55 to be moved inwardly or outwardly at twice the rate at which the rod 46 carrying clamps 40, 4| are similarly moved.

A single plate I2 may be held on the cylinder, as shown in Figure 6,'where the force of springs 33 is transmitted to clamps 4| through rods 30 and 46, nuts 53, clamps 40 and springs 41, rather than through an outer plate I4.

The inner edge of the inner plate I2 is securely held by ring I6 throughout its length and the several lugs 43 insure the outer edge of this plate being securely h-eld regardless of considerable irregularity in the edge of the plate, at the same time completely avoiding any excessive application of force to the edge of the plate. The outer plate I4 is held resiliently along both edges at a plurality of points by the lugs 42 and clamps 55, similarly securely holding the plates without possible damage, and the clamps conform to the edges of the plate even if the edges are warped, not parallel or are otherwise not accuratel cut.

It will be observed from the foregoing description, taken in connection with the drawings, that as theintermediate clamps 40- and 4| are slidably mounted on the section 46 of the motion transmitting rod 30, which extends there- 1 through, and are thusloosely interconnected with the outer clamping member 30, which is fixed by its threaded connection with the'rod for movements therewith, and that as the clamps 4|] and 4| are controlled in their movements by their spring 41, which is weaker than the spring 33, and by the stop members 45 and 53, the construction described not only adapts the clamps 40 and 4| for effective resilient clamping actions on the printing plates, in which each clamp is independently adjustable with relation to the other on the rod section 46, but also adapts said clamps 4n and 4| for variable clamping actions to suit printing conditions and to clamp with firmness any printing plates whose edges are not exactly true. 7

As shown in Fig. 5, when an outer printing plate I2 and an inner printing plate I4" are to be clamped in place, with the rod 30 arranged in retracted position, the clamps 4|! and 4| are so disposed that the inward movement of clamp 4| is limited by stop 45 While either clamp is free to be moved outward and said clamps are under the pressure influence solely of their comparatively weak spring 47. Hence the inner plate I2 may be easily applied, as.the clamp 43 may be readily moved outward as the plate I2 is being inserted between the same and the center ring I6 and will then spring inward to grip the outer edge of the plate. In the application of plate I4, which is first engaged at its inner edge with the clamp 40, lock plate 28 is moved inward to tension the spring 33 and transmit inward motion therethrough t rod 30, whereby the outer clamp 36 will be moved inward to engage the outer edge of the plate I4 and to transmit motion through said plate to the clamp 40 to compress the spring 41 and bring the two clamps 4|] and 4| into abutting engagement, as shown in Fig. 4, and cause the clamps 40 and 4| to firmly engage the adjacent edges of the plates I2 and I4 and force the plate I2 against the ring I6, whereby both plates will be securely but, resiliently gripped at their inner and outer edges. When the plates are so gripped the spring 33 Will not only securely hold the outer clamp 36 in clamping position, but will also hold the lighter spring 41 compressed and under tension to maintain the clamps 40 and 4| in resilient gripping engagement with the plates I2 and I4. When so engaged, the clamps 40 and 4|"are. slightly spacedfrom the stops 45 and 53 so that each may move inwardly and outwardly to compensate for any possible contraction and expansion of the applied plates or variations in their edges from an exactly true and parallel relation.

In the event that an inner plate I2 is to be clamped in position for use without an outer plate I4, the parts will be operated as shown in Fig. 6. With the" parts in the position shown in Fig. .5 the inner plate I2 is inserted between the inner ring I6 and the intermediate clamping member 4 whereby it will be loosely held. Plate 28 is then moved inwardly and locked in position. This movement of plate 28 compresses the spring 33, thus forcing rod 30 inwardly so as to bring stop 53 into engagement with the outer intermediate clamping member 40 to place spring 41 under compression and to force the clamping member 40 toward the clamping member 4| and the latter into engagement with the plate I2. Thus the plate I2 may be clamped in working position even in the absence of a plate I4 at the same side of the center of the cylinder.

The clamping members 40 and 4| are, as before stated, arranged in working pairs, with the body portions of each pair arranged opposite each other and in parallel relation to each other. Thus, when the pairs 42, 43 of a pair of members grip straight parallel portions of the edges of the plates I2 and I4, or where such portions of the edges project beyond other portions of the edges, the body portions of the members 4|! and 4| may fit closely together or directly abut to compensate for and firmly clamp the projecting portions of the edges. On the other hand, if the jaws of a pair of opposed members 40 and 4| should engage untrue, irregular or inset portions of the edges of the plates, the independent slida-ble mounting of the members 40 and 4| on the rod section 46 will allow the members to spread and their jaws 42 and 43 to be resiliently held in engagement with the untrue edges of the plates by the pressure of the spring 41. It w ll be noted that the laws 42 and 43 of the members 40 and 4| are of greater width than the body portions of the members and that the jaw of each member projects laterally, to equal degrees beyond opposite sides of the member. Hence the jaws are adapted to have a long range of bearing on the edges of the plates to grip either regular or irregular portions of the edges of the plates with great security.

The invention in its broader aspects is not limited to the specific mechanisms shown and described but departures may be made therefrom within the scope of the accompanying claims without departing from the principles of the invention and without sacrificing its chief advantages.

What I claim is:

1. A plate clamping mechanism for a printing cylinder adapted for use as one of a group about the cylinder including in combination a fixed center ring, a motion transmitting member, a pair of intermediate plate clamps slidable on said motion transmitting member toward and from each other, an end plate clamp movable with the motion transmitting member, spring means urging the intermediate clamps apart, spring means urging the motion transmitting member and end clamp towards the center ring, and means for applying the pressure of the second named spring means through the motion transmitting member and first named spring means to the intermediate clamps so that a single platetmay be resiliently clamped between the center ring and one intermediate plate clamp or in addition another plate between the other intermediate plate clamp and the end clamp.

2. A clamping mechanism for a printing cylinder adapted for use as one of a group about the cylinder including in combination a fixed center ring, a pair of slidable intermediate plate clamps on the cylinder, an end clamp for the outer edge of an outer plate, spring means urging the outer clamp inwardly, spring means urging the pair of clamps away from each other, and a motion transmitting rod interconnecting the intermediate clamps with the outer clamp and on which the intermediate clamps are slidably mounted for movements toward and from each other, whereby spring pressure normally urging the outer clamp inwardly may be transferred though the rod and second named spring means to the intermediate clamps when the outer plate is not used.

3. A plate clamping mechanism for a printing cylinder adapted for use as one of a group about the cylinder, including in combination a fixed center ring, a pair of slidable intermediate plate clamps on the cylinder, an end clamp for the outer edge of the outer plate, a spring urging the outer clamp inwardly, a spring urging the pair of clamps away from each other, and a rod on which the intermediate clamps are slidably mounted for movements toward and from each other, said rod loosely interconnecting the intermediate clamps with the outer clamp and having limited longitudinal inward and outward movements relative to the intermediate clamps, whereby pressure of the first named spring urging the outer clamp inwardly may be transferred through the rod and second named spring to the intermediate clamps when an outer plate is not used.

4. A plate clamping mechanism for a printing cylinder adapted for use as one of a group about the cylinder including in combination a fixed center ring forming a center stop, a pair of slidable intermediate plate clamps and an outer plate clamp on the cylinder, a strong spring for urging the end clamp inwardly, a spring of less strength than the first named spring disposed between the intermediate clamps to urge them apart, a rod extending loosely through the intermediate clamps and slidably supporting the same for movements toward and from each other and loosely interconnecting the end clamp with said intermediate clamps, and abutments on the rod for limiting the movements of the intermediate clamps away from each other and whereby pressure of the first named spring urging the outer clamp inwardly may be transferred through the rod and second named spring to the intermediate clamps when the outer plate is not used.

'5. A plate clamping mechanism for a printing cylinder adapted for use as one of a group about the cylinder including in combination a fixed center ring forming a center stop, a pair of slidable intermediate plate clamps and. an outer plate clamp on the cylinder, spring means urging the end clamp inwardly, a spring between the intermediate clamps to urge them apart, an inwardly and outwardly sliding rod directly connected to the end clamp and extending loosely through and slidably supporting the intermediate clamps thereon for movements toward and from eachother and loosely interconnecting the end clamp with said intermediate clamps, and means for tensioning said spring means to force the rod inwardly by the'spring pressure of said spring means and to transmit pressure therethrough to and through the spring between the intermediate clamps to move said intermediate clamps to clamping position when an outer plate is not used.

6. A plate clamping mechanism for a printing cylinder adapted for use as one of a group about the cylinder including in combination a fixed center ring forming a center stop, a pair of slidable intermediate plate clamps and an outer plate clamp on the cylinder, 'a strong spring for urging the end clamp inwardly, a relatively weaker spring between the intermediate clamps for urging them apart, and a rod threadedly connected with the outer clamp and extending loosely through and slidably supporting the intermediate clamps thereon for movements toward and from each other and loosely interconnecting the end clamp and intermediate clamps to adapt the rod to be forced inwardly by the spring pressure of the first named spring and to transmit clamping motion through the second named spring to the intermediate clamps when the outerplate is not used, said threaded means adjustably coupling the outer clamp to the rod for movements therewith axially of the cylinder. 7 l Y CURTIS S. CRAFTS; 

